In most cases, an ultraviolet chip has the form of a flip chip in which an electrode is formed in a lower portion thereof. In order to mount a chip having a flip chip structure on a substrate, a sub-mount is used in view of the position of an electrode and the flatness of a substrate.
Specifically, in a ceramic package of related art, a sub-mount of the type in which an electrode is coated on a silicon wafer mounted with a chip is bonded to an electrode portion formed on a ceramic substrate. The electrode formed on the silicon wafer is bonded to an electrode of an ultraviolet flip chip, thereby mounting the chip.
According to this method, it is necessary to perform an additional step of mounting the sub-mount on the ceramic substrate. Due to the structural feature (epoxy adhesive agent) for mounting the sub-mount, there is posed a problem in that the heat generated in the ultraviolet chip cannot be effectively transferred to a metal substrate, as a result of which the lifespan of the ultraviolet-curable adhesive agent is reduced.